Joel Kotkin writing in the Washington Post about the inevitable decline of the modern city:  He argues that cities have been losing population since 2000 as a direct result of terrorism concerns. 

The kinds of policies needed to secure their safety may pose a serious dilemma for great cities that have been built upon the values of openness, freedom of movement, privacy, tolerance and due process. Yet to survive, these same cities may now need to shift their primary focus to protecting their people, their commerce and their future against those who seek to undermine and even, ultimately, destroy them.